The present invention relates to a graft polymer, more particularly to a fluorinated cyclic olefinic graft polymer.
Organic polymers have been known for their commercial application in making dielectric materials such as electrets. Typically, the organic polymers are made into electrets by charge injection. Unfortunately, the electrets prepared by charge injection may result in a surface charge that is vulnerable to degradation by dust and humidity. Charge injection via electron beam has been suggested to alleviate this problem because it implants the charge below the surface. Thus, the environmental degradation was somewhat reduced.
Conventional electrets could also be made from a combination of olefinic compounds and polymeric compounds. Japanese Laid Open Publication No. 08-041260 disclosed a composition which contains a cyclic olefinic resin and a modified polymeric compound prepared by graft polymerization of at least one modifying monomer selected from an unsaturated carboxylic acid and its derivative with a polymeric compound. U.S. Pat. No 6,107,422 to Wang et al. disclosed a copolymer of an olefin and an unsaturated partially fluorinated functionalized monomer. However, the fluorinated electret materials currently available have limited applicability and performance due to high production costs, low charge retention, and low structural strength. And it is also difficult to process currently available fluorinated electret material by injection molding.